KR20230159373A - Manufacturing method of adhesive tape for semiconductor processing and semiconductor device - Google Patents

Abstract

(Project) To provide an adhesive tape for semiconductor processing that can suppress chip cracking when peeling off the adhesive tape.
(Solution) An adhesive tape having a base material and an adhesive layer, wherein one side of the adhesive layer is exposed to the air atmosphere and the adhesive tape is irradiated with ultraviolet rays under conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2. An adhesive tape for semiconductor processing, wherein the surface elastic modulus of the exposed surface of the layer is 5 MPa or more.

Description

Adhesive tape for semiconductor processing and manufacturing method of semiconductor device

The present invention relates to an adhesive tape for semiconductor processing. More specifically, the present invention relates to an adhesive tape for semiconductor processing, and more specifically, to provide a groove on the surface of the wafer or to provide a modified area inside the wafer using a laser, and to separate the wafer into individual pieces due to stress during grinding of the back side of the wafer. It relates to an adhesive tape preferably used to temporarily hold a semiconductor wafer or chip when manufacturing a semiconductor device using a method, and a method of manufacturing a semiconductor device using the adhesive tape.

As various electronic devices become smaller and more functional, the semiconductor chips mounted on them are also required to be smaller and thinner. In order to make chips thinner, it is common to grind the back side of a semiconductor wafer to adjust the thickness. In addition, in order to obtain thinner chips, a groove of a predetermined depth is formed from the front side of the wafer with a dicing blade, then grinding is performed from the back side of the wafer, and the wafer is broken into pieces by grinding to obtain chips. In some cases, a method called DBG (Dicing Before Grinding) is used. In DBG, the backside grinding of the wafer and the separation of the wafer into pieces can be performed simultaneously, so thin chips can be manufactured efficiently.

Additionally, in recent years, as a modification of the sun dicing method, a method has been proposed in which a modified region is provided inside the wafer with a laser and the wafer is separated into pieces using stress during grinding the back side of the wafer. Hereinafter, this method may be referred to as LDBG (Laser Dicing Before Grinding). In LDBG, the wafer is cut in the crystal direction starting from the modified region, so the occurrence of chipping can be reduced compared to the pre-dicing method using a dicing blade. As a result, a chip with excellent bending strength can be obtained and can also contribute to further thinning of the chip. In addition, compared to DBG, which forms a groove of a predetermined depth on the surface of the wafer with a dicing blade, there is no area where the wafer is shaved off with a dicing blade, that is, the kerf width is extremely small, so the chip Yield is excellent.

Conventionally, when grinding the backside of a semiconductor wafer or manufacturing chips using DBG or LDBG, an adhesive tape called a backgrind sheet is applied to the wafer surface to protect the circuitry on the wafer surface and to maintain the semiconductor wafer and semiconductor chips. It is common to attach a . After backside grinding, an adhesive tape with an adhesive layer is attached to the ground surface. Thereafter, the adhesive tape affixed to the wafer surface is peeled off after its adhesive strength is reduced by irradiating energy rays such as ultraviolet rays. Through this process, an adhesive tape is attached to the back side of the wafer.

Here, in Patent Document 1, an adhesive tape having an adhesive layer using an adhesive having a reduction rate of 60% or more in tack force after irradiation with ultraviolet rays in the presence of oxygen is proposed. However, when using the tape described in Patent Document 1, when the finished chip thickness is thinned to about 30㎛, chip defects or damage (hereinafter referred to as “chip cracks”) occur when peeling off the adhesive tape. There were cases where this occurred.

Japanese Patent Publication No. 2015-185691

As a result of careful study to solve the above problem, the present inventors found that due to the thinner thickness of the semiconductor wafer after grinding, there were areas where the adhesive strength was not sufficiently reduced even when irradiated with energy rays such as ultraviolet rays on the adhesive tape. , it was discovered that cracks occurred in the chip when peeling off the adhesive tape.

FIG. 1 is a schematic diagram showing how the thickness of the semiconductor wafer 20 gradually becomes thinner when the back side of the semiconductor wafer 20 to which the adhesive tape 10 is attached is ground. In Figure 1, (1) shows the state before back side grinding, (3) shows when the thickness of the semiconductor wafer is about 30㎛, and (2) shows the state from (1) to (3) above. It shows the state along the way. Normally, as shown in (1) of FIG. 1, the side surface of the semiconductor wafer 20 before grinding is round. The adhesive tape 10 protects the circuitry on the wafer surface and usually includes a material that is flat and hard enough to hold the wafer and chips. Therefore, when the adhesive tape 10 is attached to the wafer 20 before grinding, as shown in FIG. 1 (1), the adhesive tape adheres slightly to the outer edge of the wafer 20. There are areas where it doesn't work.

As shown in FIG. 1, as (1), (2), (3) and back side grinding of the wafer progress, the thickness of the semiconductor wafer 20 becomes thinner and the size changes, but the size of the adhesive tape 10 also changes. There is no Then, when the back side of the wafer is ground to make the thickness very thin to about 30 μm, the round portion on the side of the wafer 20 is removed, as shown in (3) of FIG. 1. Then, even when the shape of the adhesive tape is approximately the same as that of the wafer before grinding, as shown in (1) of FIG. 1, after grinding, the adhesive tape 10 is formed at the outer periphery of the wafer 20, as shown in (3) of FIG. 1. The outer edge is exposed. If the adhesive tape is irradiated with energy rays such as ultraviolet rays in this state, the adhesive strength is sufficiently reduced in the portion of the adhesive tape that is in close contact with the wafer. However, in the portion of the adhesive tape that is not in close contact with the wafer and is exposed to the atmosphere (exposed portion of the outer edge), curing of the adhesive is inhibited by oxygen in the atmosphere, and the adhesive strength is not sufficiently reduced even by irradiation of energy rays such as ultraviolet rays. No. That is, the adhesive tape has uncured portions even after irradiation of energy rays such as ultraviolet rays.

For example, a dicing/die bonding tape is attached to the back side of the wafer after back side grinding as an adhesive tape. 2 and 3 are schematic diagrams of a laminate in which a dicing/die-bonding tape 30 is further attached to a semiconductor wafer 20 after grinding the back side to which the adhesive tape 10 is attached. The dicing/die bonding tape 30 includes an adhesive layer (not shown) and is attached to the semiconductor wafer 20 by the adhesive layer. FIG. 3 shows the state in which the dicing/die bonding tape 30 is attached to a semiconductor wafer 20 that has been back ground to a very thin thickness of about 30 μm. Meanwhile, FIG. 2 shows a state where the dicing/die-bonding tape 30 is attached to the semiconductor wafer 20, and the thickness of the semiconductor wafer 20 is greater than that of FIG. 3. As shown in FIG. 2, when the thickness of the semiconductor wafer 20 after back-side grinding is larger, even if the dicing die-bonding tape 30 is attached, the uncured portion of the adhesive tape 10 is It does not contact the adhesive layer of the bonding tape 30. However, as shown in FIG. 3, when the thickness of the semiconductor wafer 20 after back side grinding is very thin to about 30 μm, when the dicing die-bonding tape 30 is attached, the adhesive tape 10 may be damaged. There is a risk that the hardened portion may come into contact with the adhesive layer of the dicing/die-bonding tape 30 and stick to it. Dicing/die bonding tape is not cut like a wafer. Therefore, when an attempt is made to peel off the adhesive tape attached to the dicing/die-bonding tape, the adhesive tape and the dicing/die-bonding tape become integrated, and the dicing/die-bonding tape also curves along with the curvature of the adhesive tape. In addition, the wafer or chip sandwiched between the adhesive tape and the dicing/die bonding tape is also curved at the same time. As a result, it becomes easy for cracks to occur in the chip. Additionally, the adhesive layer of the dicing/die bonding tape may be damaged due to curvature, and its fragments may fall off.

In other words, areas where the adhesive strength does not sufficiently decrease even when irradiated with energy rays such as ultraviolet rays are created on the adhesive tape, so that when the thickness of a semiconductor wafer is made very thin by back-side grinding, chip cracks occur when the adhesive tape is peeled off. The problem was that it was becoming easier for this to happen.

The present invention has been made in consideration of the above-described prior art, and its purpose is to provide an adhesive tape for semiconductor processing that can suppress chip cracking when peeling off the adhesive tape.

The gist of the present invention aimed at solving these problems is as follows.

(1) An adhesive tape having a base material and an adhesive layer,

With one side of the adhesive layer exposed to the atmospheric atmosphere, the surface elastic modulus of the exposed side of the adhesive layer is 5 MPa or more after irradiating ultraviolet rays to the adhesive tape under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2, a semiconductor Adhesive tape for processing.

(2) The adhesive layer contains an acrylic resin,

The adhesive tape for semiconductor processing according to (1), wherein the content of HEMA-derived polymerized units is 6 parts by mass or more with respect to the total amount of 100 parts by mass of the acrylic resin.

(3) With one side of the adhesive layer exposed to the air atmosphere, the surface free energy of the exposed side of the adhesive layer after irradiating ultraviolet rays to the adhesive tape under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2 is The adhesive tape for semiconductor processing according to (1) or (2), which is less than 36 mJ/m2.

(4) attaching the adhesive tape for semiconductor processing according to any one of (1) to (3) above to the surface of a semiconductor wafer, and cutting the adhesive tape along the outer periphery of the semiconductor wafer;

A process of forming a groove from the front side of the semiconductor wafer, or forming a modified region inside the semiconductor wafer from the front or back side of the semiconductor wafer;

A process of grinding a semiconductor wafer on which the adhesive tape is attached to the surface and on which the groove or the modified region is formed, from the back side, and dividing the semiconductor wafer into a plurality of chips using the groove or the modified region as a starting point;

Process of peeling the adhesive tape from the plurality of chips

A method of manufacturing a semiconductor device comprising:

(5) The method for manufacturing a semiconductor device according to (4), further comprising the step of attaching a dicing/die bonding tape to the back side of a semiconductor wafer.

In the adhesive tape for semiconductor processing according to the present invention, the adhesive strength of the adhesive layer can be sufficiently reduced in an atmospheric atmosphere. As a result, the occurrence of cracks in the semiconductor chip can be suppressed.

1 is a schematic diagram showing the progress of backside grinding of a semiconductor wafer.
FIG. 2 is a schematic diagram of a laminate made of the adhesive tape 10, the semiconductor wafer 20 after back side grinding, and the dicing/die bonding tape 30, when the thickness of the semiconductor wafer 20 is greater than FIG. 3. represents.
Figure 3 is a schematic diagram of a laminate consisting of an adhesive tape 10, a semiconductor wafer 20 after back side grinding, and a dicing/die bonding tape 30, wherein the semiconductor wafer 20 is very thin down to about 30 μm in thickness. This indicates a grinding state.
Fig. 4 is a schematic diagram showing the adhesive tape according to this embodiment.
Figure 5 is a schematic diagram of a laminate consisting of an adhesive tape, a semiconductor wafer 20 after back side grinding, and a dicing/die bonding tape 30 according to the present embodiment, wherein the semiconductor wafer 20 has a thickness of about 30 μm. If it is very thin, it indicates that it has been ground.

Below, the adhesive tape for semiconductor processing according to the present invention will be described in detail. First, the main terms used in this specification will be explained.

In this specification, for example, “(meth)acrylate” is used as a word representing both “acrylate” and “methacrylate”, and the same applies to other similar terms.

“For semiconductor processing” means that it can be used in various processes such as conveyance of semiconductor wafers, back side grinding, dicing, and pickup of semiconductor chips.

The “surface” of a semiconductor wafer refers to the surface on which circuits are formed, and the “back surface” refers to the surface on which circuits are not formed.

Separation of a semiconductor wafer refers to dividing a semiconductor wafer into individual circuits to obtain semiconductor chips.

DBG refers to a method of forming a groove of a predetermined depth on the front side of a wafer, then grinding the wafer from the back side, and breaking the wafer into pieces by grinding. The groove formed on the surface side of the wafer is formed by a method such as blade dicing, laser dicing, or plasma dicing. In addition, LDBG is a modified example of DBG, and refers to a method of providing a modified area inside the wafer with a laser and separating the wafer into individual pieces using stress during grinding the back side of the wafer.

Next, the configuration of each member of the adhesive tape for semiconductor processing according to the present invention will be described in more detail. In addition, the adhesive tape for semiconductor processing according to the present invention may simply be described as “adhesive tape.”

In this embodiment, as shown in FIG. 4, the adhesive tape 100 means a laminate including a base material 110 and an adhesive layer 120. The adhesive tape 100 may have a buffer layer on at least one side of the substrate 110. Moreover, it does not prevent the inclusion of other constituent layers other than these. For example, a primer layer may be formed on the surface of the substrate on the adhesive layer side, and a release sheet for protecting the adhesive layer until use may be laminated on the surface of the adhesive layer. Additionally, the base material may be a single layer or may be a multilayer. The same applies to the adhesive layer and buffer layer.

Below, the structure of each member of the adhesive tape for semiconductor processing according to this embodiment is explained in more detail.

○ Adhesive layer

In the adhesive tape according to this embodiment, the exposed surface of the adhesive layer after irradiating ultraviolet rays to the adhesive tape under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2 with one side of the adhesive layer exposed to the atmospheric atmosphere. The surface elastic modulus is 5 MPa or more, preferably 6 MPa or more, and more preferably 6.5 MPa or more. By setting the surface elastic modulus within the above range, the adhesive force of the adhesive layer can be sufficiently reduced, and as a result, the occurrence of chip cracks can be suppressed. In addition, the upper limit of the surface elastic modulus is not particularly limited, but is usually 17 MPa, preferably 14 MPa.

In the measurement of the surface elastic modulus, ultraviolet rays are irradiated from the substrate side. Additionally, the surface elastic modulus is measured using an atomic force microscope. Specifically, a cantilever made of silicon nitride (tip radius: 2 nm, resonance frequency: 70 kHz, spring constant: 0.4 N/m) installed in an atomic force microscope was pressed into the surface of the adhesive layer at room temperature with a press amount of 5. Press-fitting is performed at 5 nm and a scan speed of 5 Hz, and removal is performed. The obtained force curve (the horizontal axis is the sample deformation amount and the vertical axis is the measured load) is fitted with the JKR theoretical equation to calculate the surface elastic modulus. The average value of the values obtained by measuring 4096 points on the surface of the adhesive layer (5 μm × 5 μm) is taken as the surface elastic modulus (MPa).

The surface elastic modulus can be controlled by preparing the adhesive layer to contain an acrylic resin and also adjusting the amount of polymerized units derived from 2-hydroxyethyl methacrylate (hereinafter sometimes abbreviated as HEMA). there is. In particular, the surface elastic modulus can be controlled within the above range by preparing the adhesive layer so that the content of polymerized units derived from HEMA is 6 parts by mass or more with respect to the total amount of 100 parts by mass of the acrylic resin.

In the adhesive tape according to this embodiment, with one side of the adhesive layer exposed to the air atmosphere, the exposed side of the adhesive layer after irradiating ultraviolet rays to the adhesive tape under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2 The surface free energy is preferably less than 36 mJ/m 2 , more preferably 32 mJ/m 2 or less, and preferably 30 mJ/m 2 or less. From the viewpoint of sufficiently reducing the adhesive force of the adhesive layer, it is preferable that the surface free energy is within the above range. In addition, the lower limit of the surface free energy is not particularly limited, but is usually 18 mJ/m2, and is preferably 22 mJ/m2.

In the measurement of the surface free energy, ultraviolet rays are irradiated from the substrate side. In addition, the surface free energy is determined by measuring the contact angle (measurement temperature: 25°C) of various liquid droplets and using the Kitazaki and Hata method based on the value of the contact angle. Specifically, diiodomethane, 1-bromonaphthalene, and distilled water were used as droplets, and the contact angle (measurement temperature: 25°C) was measured by a static method in accordance with JIS R 3257:1999, and the contact angle was Based on the value, the surface free energy (mJ/m2) is determined by the Kitazaki and Hata method.

The surface free energy can be controlled by preparing the adhesive layer to contain an acrylic resin and further adjusting the amount of polymerized units derived from HEMA. In particular, the surface free energy can be controlled within the above range by preparing the adhesive layer so that the content of polymerized units derived from HEMA is 6 parts by mass or more with respect to the total amount of 100 parts by mass of the acrylic resin.

In addition, in the adhesive tape according to this embodiment, with one side of the adhesive layer exposed to the atmospheric atmosphere, ultraviolet rays are irradiated to the adhesive tape under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2, and the adhesive layer is exposed. After attaching a PMMA plate to the surface at 23°C and 50%RH under the condition of one reciprocation with a 2kg roll and leaving it for 30 minutes, the peeling strength when peeling the adhesive tape 180° is preferably 1600mN/25. mm or less, more preferably 1100 mN/25 mm or less, further preferably 980 mN/25 mm or less, and particularly preferably 800 mN/25 mm or less. From the viewpoint of sufficiently reducing the adhesive force of the adhesive layer, it is preferable to set the peel strength within the above range. In addition, the lower limit of the peeling strength is not particularly limited, but is usually 50 N/25 mm, and is preferably 80 N/25 mm.

In addition, in the measurement of the peel strength, ultraviolet rays are irradiated from the substrate side. In addition, PMMA is polymethyl methacrylate, and the PMMA plate has a thickness of 2 mm, a width of 70 mm, and a length of 150 mm, manufactured by Mitsubishi Chemical Corporation. Use the product “ACRYLITE L001”. The peel strength is measured under the conditions of a width of the adhesive tape of 25 mm, a peel speed of 300 mm/min, and a measurement temperature of 25°C, and the average value when the measurement is repeated twice under the same conditions is taken as the peel strength.

The peel strength can be controlled by preparing the adhesive layer to contain an acrylic resin and further adjusting the amount of polymerized units derived from HEMA. In particular, the peeling strength can be controlled within the above range by preparing the adhesive layer so that the content of polymerized units derived from HEMA is 6 parts by mass or more with respect to the total amount of 100 parts by mass of the acrylic resin.

In addition, in the adhesive tape according to this embodiment, exposure of the adhesive layer after irradiating ultraviolet rays to the adhesive tape under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2 with one side of the adhesive layer exposed to the atmospheric atmosphere. The adhesion energy of the surface is preferably 0.220 J/m 2 or less, more preferably 0.200 J/m 2 or less, and even more preferably 0.190 J/m 2 or less. From the viewpoint of sufficiently reducing the adhesive force of the adhesive layer, it is preferable that the adhesion energy is within the above range. In addition, the lower limit of the adhesion energy is not particularly limited, but is usually 0.12 J/m2, and is preferably 0.14 J/m2.

In the measurement of the adhesion energy, ultraviolet rays are irradiated from the substrate side. Additionally, adhesion energy is measured using an atomic force microscope. Specifically, a cantilever made of silicon nitride (tip radius: 2 nm, resonance frequency: 70 kHz, spring constant: 0.4 N/m) installed in an atomic force microscope was pressed into the surface of the adhesive layer at room temperature with a press amount of 5. Press-fitting is performed at 5 nm and a scan speed of 5 Hz, and removal is performed. The obtained force curve (the horizontal axis is the sample deformation amount and the vertical axis is the measured load) is fitted with the JKR theoretical equation to calculate the adhesion energy. The average value of the values obtained by measuring 4096 points on the surface of the adhesive layer 5 μm × 5 μm is taken as adhesion energy (J/m 2 ).

The adhesion energy can be controlled by preparing the adhesive layer to contain an acrylic resin and adjusting the amount of polymerized units derived from HEMA. In particular, the adhesion energy can be controlled within the above range by preparing the adhesive layer so that the content of polymerized units derived from HEMA is 6 parts by mass or more with respect to the total amount of 100 parts by mass of the acrylic resin.

As described above, the thickness of the adhesive layer is not particularly limited as long as the peeling strength of the adhesive layer after irradiation with ultraviolet rays in a state exposed to the air atmosphere is 1600 mN/25 mm or less, but is preferably less than 100 μm, and is more preferred. Typically, it is 5 to 80 ㎛, more preferably 10 to 70 ㎛.

In addition, the adhesive layer is not particularly limited as long as the peeling strength after irradiation with ultraviolet rays in a state exposed to the air atmosphere as described above is not more than 1600 mN/25 mm, but is preferably formed of an acrylic adhesive. Additionally, the adhesive layer is preferably formed of an energy ray-curable adhesive. Additionally, “energy ray” refers to ultraviolet rays, electron beams, etc., and ultraviolet rays are preferably used.

Hereinafter, specific examples of the adhesive will be described in detail, but these are non-limiting examples, and the adhesive layer in the present invention should not be construed as limited to these.

[Adhesive composition]

Examples of the energy ray curable adhesive forming the adhesive layer include, for example, an energy ray curable adhesive composition containing an energy ray curable compound other than the adhesive resin in addition to a non-energy ray curable adhesive resin (also referred to as “adhesive resin I”). (hereinafter also referred to as “type X adhesive composition”) can be used. In addition, as an energy ray curable adhesive, it contains as a main component an energy ray curable adhesive resin (hereinafter also referred to as “adhesive resin II”) in which an unsaturated group is introduced into the side chain of the non-energy ray curable adhesive resin, and energy rays other than the adhesive resin. An adhesive composition (hereinafter also referred to as “Y-type adhesive composition”) that does not contain a pre-curable compound may also be used.

In addition, as an energy ray curable adhesive, a combination type of X type and Y type, that is, an energy ray curable adhesive composition (hereinafter referred to as “ You may use a “type adhesive composition”).

Among these, it is preferable to use an XY type adhesive composition. By using an

However, the adhesive may be formed from a non-energy ray curable adhesive composition that does not harden even when irradiated with energy rays. The non-energy ray curable adhesive composition contains at least the non-energy ray curable adhesive resin I, but does not contain the above-mentioned energy ray curable adhesive resin II and the energy ray curable compound.

In addition, in the following description, “adhesive resin” is used as a term referring to one or both of the above-described adhesive resin I and adhesive resin II. Specific examples of the adhesive resin include acrylic resin, urethane resin, rubber resin, and silicone resin, but acrylic resin is preferred.

Hereinafter, an acrylic adhesive in which an acrylic resin is used as the adhesive resin will be described and explained in more detail.

For acrylic resin, an acrylic polymer is used. The acrylic polymer is obtained by polymerizing a monomer containing at least alkyl (meth)acrylate, and contains structural units derived from alkyl (meth)acrylate. Examples of the alkyl (meth)acrylate include those in which the alkyl group has 1 to 20 carbon atoms, and the alkyl group may be linear or branched. Specific examples of alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl Sil (meth)acrylate, etc. can be mentioned. Alkyl (meth)acrylates may be used individually or in combination of two or more types.

Additionally, from the viewpoint of improving the adhesive strength of the adhesive layer, the acrylic polymer preferably contains a structural unit derived from an alkyl (meth)acrylate whose alkyl group has 4 or more carbon atoms. The carbon number of the alkyl (meth)acrylate is preferably 4 to 12, more preferably 4 to 6. Moreover, the alkyl (meth)acrylate whose alkyl group has 4 or more carbon atoms is preferably an alkyl acrylate.

In the acrylic polymer, the content of alkyl (meth)acrylate in which the alkyl group has 4 or more carbon atoms is preferably 35 to 98 parts by mass, based on 100 parts by mass of the total amount of monomers constituting the acrylic polymer (hereinafter simply referred to as "total amount of monomers"). parts, more preferably 45 to 95 parts by mass, and still more preferably 50 to 90 parts by mass.

In addition to the structural units derived from alkyl (meth)acrylates having an alkyl group having 4 or more carbon atoms, the acrylic polymer is derived from alkyl (meth)acrylates having an alkyl group having 1 to 3 carbon atoms in order to adjust the elastic modulus and adhesive properties of the adhesive layer. It is preferable that it is a copolymer containing structural units. Moreover, the alkyl (meth)acrylate is preferably an alkyl (meth)acrylate having 1 or 2 carbon atoms, more preferably methyl (meth)acrylate, and most preferably methyl methacrylate. In the acrylic polymer, the content of alkyl (meth)acrylate whose alkyl group has 1 to 3 carbon atoms is preferably 1 to 30 parts by mass, more preferably 3 to 26 parts by mass, based on 100 parts by mass of the total amount of monomer. More preferably, it is 5 to 22 parts by mass.

The acrylic polymer preferably has structural units derived from functional group-containing monomers in addition to the structural units derived from the alkyl (meth)acrylate described above. Functional groups of the functional group-containing monomer include hydroxyl group, carboxyl group, amino group, and epoxy group. The functional group-containing monomer can react with a crosslinking agent described later to become a crosslinking origin, or react with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer.

Examples of functional group-containing monomers include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, and epoxy group-containing monomers. In this embodiment, it is preferable to use HEMA in particular as the functional group-containing monomer in a predetermined amount or more.

Here, in the adhesive tape according to the present embodiment, the adhesive layer contains an acrylic resin, and the content of the polymerized unit derived from HEMA is preferably 6 parts by mass or more with respect to 100 parts by mass of the total amount of acrylic resin. The content of polymerized units derived from HEMA may be furthermore 10 parts by mass or more, or 12 parts by mass or more. In preparing the pressure-sensitive adhesive layer, by using the content of the HEMA-derived polymerized unit within the above range, the peel strength, surface free energy, surface modulus of elasticity, and adhesion energy to the pressure-sensitive adhesive can be within the desired range. In addition, the upper limit of the content of the polymerized unit derived from HEMA in the adhesive layer is not particularly limited, but is usually 35 parts by mass, preferably 32 parts by mass, with respect to 100 parts by mass of the total amount of acrylic resin.

In this embodiment, hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, etc. other than HEMA may be used individually or in combination of two or more types. Among these, it is preferable to use a hydroxyl group-containing monomer and a carboxyl group-containing monomer, and it is more preferable to use a hydroxyl group-containing monomer.

As hydroxyl group-containing monomers, in addition to the above-mentioned HEMA, for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl ( Hydroxyalkyl (meth)acrylates such as meta)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; Unsaturated alcohols such as vinyl alcohol and allyl alcohol can be mentioned.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; Ethylenically unsaturated dicarboxylic acids such as fmalic acid, itaconic acid, maleic acid, and citraconic acid, and their anhydrides, and 2-carboxyethyl methacrylate.

The content of the monomer containing a functional group other than HEMA is preferably 1 to 35 parts by mass, more preferably 3 to 32 parts by mass, and still more preferably 6 to 30 parts by mass, based on 100 parts by mass of the total amount of monomers constituting the acrylic polymer. It is wealth.

In addition to the above, the acrylic polymer may also contain structural units derived from monomers copolymerizable with the acrylic monomers described above, such as styrene, α-methylstyrene, vinyl toluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

The acrylic polymer can be used as non-energy ray curable adhesive resin I (acrylic resin). Additionally, examples of the energy ray-curable acrylic resin include those obtained by reacting a functional group of the acrylic polymer I with a compound having a photopolymerizable unsaturated group (also referred to as an unsaturated group-containing compound).

An unsaturated group-containing compound is a compound that has both a substituent that can be bonded to a functional group of an acrylic polymer and a photopolymerizable unsaturated group. Examples of the photopolymerizable unsaturated group include (meth)acryloyl group, vinyl group, allyl group, vinylbenzyl group, etc., and (meth)acryloyl group is preferable.

In addition, examples of the substituent that the unsaturated group-containing compound has that can be bonded to the functional group include an isocyanate group and a glycidyl group. Therefore, examples of unsaturated group-containing compounds include (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, and glycidyl (meth)acrylate.

In addition, the unsaturated group-containing compound preferably reacts with a portion of the functional groups of the acrylic polymer, and specifically, it is preferable to react the unsaturated group-containing compound with 50 to 98 mol% of the functional groups of the acrylic polymer, 55 It is more preferable to react at ~93 mol%. In this way, in the energy ray-curable acrylic resin, a part of the functional group remains without reacting with the unsaturated group-containing compound, making it susceptible to crosslinking by a crosslinking agent.

Moreover, the weight average molecular weight (Mw) of the acrylic resin is preferably 300,000 to 1.6 million, more preferably 400,000 to 1.4 million, and still more preferably 500,000 to 1.2 million.

(Energy ray curable compound)

As the energy ray-curable compound contained in the type

Examples of such energy ray-curable compounds include trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. , polyvalent (meth)acrylate monomers such as 1,4-butylene glycol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate. , oligomers such as polyether (meth)acrylate and epoxy (meth)acrylate.

Among these, urethane (meth)acrylate oligomer is preferable because it has a relatively high molecular weight and is difficult to reduce the shear storage modulus of the adhesive layer.

The molecular weight (weight average molecular weight in the case of an oligomer) of the energy ray-curable compound is preferably 100 to 12,000, more preferably 200 to 10,000, further preferably 400 to 8,000, and particularly preferably 600 to 6,000.

The content of the energy ray-curable compound in the type It is the mass part.

On the other hand, the content of the energy ray-curable compound in the ~15 parts by mass. In the XY type adhesive composition, since the adhesive resin is energy ray curable, it is possible to sufficiently reduce the peel strength after energy ray irradiation even if the content of the energy ray curable compound is small.

(Cross-linking agent)

It is preferable that the adhesive composition further contains a crosslinking agent. The crosslinking agent, for example, crosslinks the adhesive resins by reacting with a functional group derived from a functional group-containing monomer of the adhesive resin. Examples of the crosslinking agent include isocyanate-based crosslinking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and their adducts; Epoxy-based crosslinking agents such as ethylene glycol glycidyl ether; Aziridine-based crosslinking agents such as hexa[1-(2-methyl)-aziridinyl]triphosphatriazine; Chelate-based crosslinking agents such as aluminum chelate; etc. can be mentioned. These crosslinking agents may be used individually or in combination of two or more types.

Among these, an isocyanate-based crosslinking agent is preferable from the viewpoint of increasing cohesion and improving adhesive strength and ease of availability.

From the viewpoint of promoting the crosslinking reaction, the compounding amount of the crosslinking agent is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and still more preferably 0.05 to 4 parts by mass, based on 100 parts by mass of the adhesive resin. .

(Light polymerization initiator)

In addition, when the adhesive composition is energy-ray curable, it is preferable that the adhesive composition further contains a photopolymerization initiator. By containing a photopolymerization initiator, the curing reaction of the adhesive composition can be sufficiently advanced even with relatively low-energy energy rays such as ultraviolet rays.

Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. , more specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoinmethyl ether, benzoinethyl ether. , benzoin isopropyl ether, benzylphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphos Pin oxide, 2,2-dimethoxy-2-phenylacetophenone, etc. can be mentioned.

These photopolymerization initiators may be used individually or in combination of two or more types.

The amount of the photopolymerization initiator to be added is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and still more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the adhesive resin.

(Other additives)

The adhesive composition may contain other additives as long as they do not impair the effects of the present invention. Other additives include, for example, antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, etc. When blending these additives, the blending amount of the additive is preferably 0.01 to 6 parts by mass with respect to 100 parts by mass of the adhesive resin.

In addition, the adhesive composition may be further diluted with an organic solvent to form a solution of the adhesive composition from the viewpoint of improving applicability to the substrate, buffer layer, or release sheet.

Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, etc.

In addition, these organic solvents may be the organic solvents used during the synthesis of the adhesive resin, or may be used as is, or may be used as one or more organic solvents other than the organic solvent used during the synthesis so that the solution of the adhesive composition can be applied uniformly. You can also add .

○ Description

The base material preferably has a Young's modulus of 1000 MPa or more at 23°C. If a base material with a Young's modulus of less than 1000 MPa is used, the holding performance of the adhesive tape for the semiconductor wafer or semiconductor chip is reduced, vibration during back grinding cannot be suppressed, and defects or damage to the semiconductor chip are likely to occur. . On the other hand, by setting the Young's modulus of the base material to 1000 MPa or more at 23°C, the holding performance of the semiconductor wafer or semiconductor chip by the adhesive tape increases, vibrations during back-side grinding are suppressed, and defects and damage to the semiconductor chip are prevented. can do. In addition, it becomes possible to reduce the stress when peeling the adhesive tape from the semiconductor chip, and prevent chip defects and breakage that occur when the tape is peeled. Additionally, workability when attaching the adhesive tape to a semiconductor wafer can also be improved. From this viewpoint, the Young's modulus of the substrate at 23°C is more preferably 1800 to 30000 MPa, and still more preferably 2500 to 6000 MPa.

The thickness of the base material is not particularly limited, but is preferably 110 μm or less, more preferably 15 to 110 μm, and still more preferably 20 to 105 μm. By setting the thickness of the base material to 110 μm or less, it becomes easy to control the peeling strength of the adhesive tape. Additionally, by setting it to 15 μm or more, it becomes easier for the base material to function as a support for the adhesive tape.

The material of the base material is not particularly limited as long as it satisfies the above physical properties, and various resin films can be used. Here, the substrate having a Young's modulus of 1000 MPa or more at 23°C includes, for example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and fully aromatic polyester, polyimide, polyamide, polycarbonate, Resin films such as polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, and biaxially stretched polypropylene can be mentioned.

Among these resin films, films containing at least one selected from polyester films, polyamide films, polyimide films, and biaxially stretched polypropylene films are preferred, and those containing polyester films are more preferred, and polyethylene terephthalate. It is more preferable to include a film.

Additionally, the base material may contain a plasticizer, a lubricant, an infrared absorber, an ultraviolet ray absorber, a filler, a colorant, an antistatic agent, an antioxidant, a catalyst, etc., as long as the effect of the present invention is not impaired. Additionally, the substrate may be transparent or opaque, and may be colored or vapor-deposited as desired.

Additionally, at least one surface of the substrate may be subjected to an adhesion treatment such as corona treatment in order to improve adhesion with at least one of the buffer layer and the adhesive layer. Additionally, the base material may have the above-mentioned resin film and an easily adhesive layer coated on at least one surface of the resin film.

The composition for forming an easily adhesive layer is not particularly limited, but examples include compositions containing polyester resin, urethane resin, polyester urethane resin, acrylic resin, etc. The composition for forming an easily adhesive layer may contain a crosslinking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rust preventive, a pigment, a dye, etc., as needed.

The thickness of the easily adhesive layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm. In addition, since the thickness of the easily adhesive layer in the present example is small with respect to the thickness of the base material, the thickness of the resin film having an easily adhesive layer and the thickness of the base material are substantially the same. Additionally, since the material of the easily adhesive layer is soft, the influence on Young's modulus is small, and the Young's modulus of the base material is substantially the same as the Young's modulus of the resin film even when it has an easily adhesive layer.

For example, the Young's modulus of the substrate can be controlled by selection of the resin composition, addition of a plasticizer, stretching conditions during production of the resin film, etc. Specifically, when using a polyethylene terephthalate film as a base material, as the content ratio of the ethylene component in the copolymerization component increases, the Young's modulus of the base material tends to decrease. Additionally, as the amount of plasticizer added to the resin composition constituting the base material increases, the Young's modulus of the base material tends to decrease.

○ Buffer layer

The adhesive tape according to this embodiment may have a buffer layer. The buffer layer can be provided on at least one side of the substrate, and can also be provided on both sides of the substrate. Additionally, an adhesive layer may be provided on one side of the substrate, and a buffer layer may be provided on the other side of the substrate.

The buffer layer relieves stress during grinding the back side of the semiconductor wafer and prevents cracks and defects from occurring in the semiconductor wafer. After the adhesive tape is attached to the semiconductor wafer and the adhesive tape is cut along the outer circumference, the semiconductor wafer is placed on the chuck table through the adhesive tape and the back side is ground. However, because the adhesive tape has a buffer layer as a constituent layer, the semiconductor wafer is It becomes easier to be properly maintained on the chuck table.

The buffer layer is a soft layer compared to the base material. Therefore, the Young's modulus of the buffer layer at 23°C is smaller than the Young's modulus of the substrate at 23°C. Specifically, the Young's modulus at 23°C of the buffer layer is preferably less than 1000 MPa, more preferably 700 MPa or less, and still more preferably 500 MPa or less.

The thickness of the buffer layer is preferably 1 to 100 μm, more preferably 5 to 80 μm, and still more preferably 10 to 60 μm. By setting the thickness of the buffer layer within the above range, the stress during grinding of the back surface of the buffer layer can be appropriately alleviated.

The buffer layer is preferably a cured product of a composition for forming a buffer layer containing an energy ray polymerizable compound. Additionally, the layer may be a polyolefin resin film, or may be a layer containing polyether as the main material.

Hereinafter, each component contained in the layer formed from the composition for forming a buffer layer containing an energy ray polymerizable compound and each component contained in the layer containing the polyolefin resin film will be described in order.

<Layer formed from a composition for forming a buffer layer containing an energy ray polymerizable compound>

The composition for forming a buffer layer containing an energy ray polymerizable compound can be cured by being irradiated with an energy ray.

In addition, the composition for forming a buffer layer containing an energy ray polymerizable compound preferably contains urethane (meth)acrylate (a1) more specifically. In addition to (a1), the composition for forming a buffer layer contains a polymerizable compound (a2) having an alicyclic or heterocyclic group having 6 to 20 ring atoms and/or a polymerizable compound (a3) having a functional group. It is more desirable to do so. Additionally, the composition for forming a buffer layer may contain a polyfunctional polymerizable compound (a4) in addition to the components (a1) to (a3). Additionally, the composition for forming a buffer layer preferably contains a photopolymerization initiator, and may contain other additives or resin components as long as the effect of the present invention is not impaired.

Hereinafter, each component contained in the composition for forming a buffer layer containing an energy ray polymerizable compound will be described in detail.

(Urethane (meth)acrylate (a1))

Urethane (meth)acrylate (a1) is a compound having at least a (meth)acryloyl group and a urethane bond, and has the property of polymerization and hardening by energy ray irradiation. Urethane (meth)acrylate (a1) is an oligomer or polymer.

The weight average molecular weight (Mw) of component (a1) is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, and still more preferably 10,000 to 30,000. Additionally, the number of (meth)acryloyl groups (hereinafter also referred to as “number of functional groups”) in component (a1) may be monofunctional, difunctional, or trifunctional or more, but is preferably monofunctional or difunctional.

Component (a1) can be obtained, for example, by reacting a (meth)acrylate having a hydroxy group with a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound and a polyvalent isocyanate compound. In addition, component (a1) may be used individually or in combination of two or more types.

The polyol compound serving as the raw material for component (a1) is not particularly limited as long as it is a compound having two or more hydroxy groups. Specific examples of polyol compounds include alkylene diol, polyether type polyol, polyester type polyol, and polycarbonate type polyol. Among these, polyester type polyol or polycarbonate type polyol is preferable.

Additionally, the polyol compound may be any of a bifunctional diol, a trifunctional triol, or a tetrafunctional or higher-functional polyol, but a bifunctional diol is preferable, and a polyester-type diol or polycarbonate-type diol is more preferable.

Examples of the polyvalent isocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; Alicyclic products such as isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, ω,ω'-diisocyanate and dimethylcyclohexane. diisocyanates; Aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, and naphthalene-1,5-diisocyanate. there is.

Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferable.

Urethane (meth)acrylate (a1) can be obtained by reacting a (meth)acrylate having a hydroxy group with a terminal isocyanate urethane prepolymer obtained by reacting the above-mentioned polyol compound with a polyhydric isocyanate compound. The (meth)acrylate having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and a (meth)acryloyl group in at least one molecule.

Specific examples of (meth)acrylates having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4- Hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol Hydroxyalkyl (meth)acrylates such as mono (meth)acrylate and polypropylene glycol mono (meth)acrylate; Hydroxyl group-containing (meth)acrylamide such as N-methylol (meth)acrylamide; Reactants obtained by reacting vinyl alcohol, vinyl phenol, and diglycidyl ester of bisphenol A with (meth)acrylic acid; etc. can be mentioned.

Among these, hydroxyalkyl (meth)acrylate is preferable and 2-hydroxyethyl (meth)acrylate is more preferable.

As conditions for reacting the terminal isocyanate urethane prepolymer and the (meth)acrylate having a hydroxy group, the conditions for reacting the reaction at 60 to 100°C for 1 to 4 hours in the presence of a solvent and a catalyst added as necessary are preferable.

The content of component (a1) in the composition for forming a buffer layer is preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, based on the total amount (100 parts by mass) of the composition for forming a buffer layer.

(Polymerizable compound (a2) having an alicyclic group or heterocyclic group having 6 to 20 ring atoms)

Component (a2) is a polymerizable compound having an alicyclic or heterocyclic group having 6 to 20 ring atoms, and is more preferably a compound having at least one (meth)acryloyl group, more preferably It is a compound having one (meth)acryloyl group. By using component (a2), the film-forming properties of the resulting composition for forming a buffer layer can be improved.

In addition, there is an overlap between the definition of component (a2) and the definition of component (a3) described later, but the overlapping portion is included in component (a3). For example, a compound having at least one (meth)acryloyl group, an alicyclic or heterocyclic group having 6 to 20 ring atoms, and a functional group such as a hydroxyl group, an epoxy group, an amide group, or an amino group is component (a2). and component (a3), but in the present invention, the above compound is included in component (a3).

The number of ring atoms of the alicyclic group or heterocyclic group of component (a2) is preferably 6 to 20, more preferably 6 to 18, further preferably 6 to 16, especially preferably 7 to 12. . Examples of the atom forming the ring structure of the heterocyclic group include a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom.

In addition, the number of ring-forming atoms refers to the number of atoms constituting the ring itself of a compound with a structure in which atoms are bonded in a ring, and refers to the number of atoms not constituting the ring (for example, atoms bonded to atoms constituting the ring). Hydrogen atoms) and atoms included in the substituent when the ring is substituted by a substituent are not included in the number of ring forming atoms.

Specific examples of component (a2) include isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, (meth)acrylates containing alicyclic groups such as cyclohexyl (meth)acrylate and adamantane (meth)acrylate; Heterocyclic group-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate; etc. can be mentioned.

In addition, component (a2) may be used individually or in combination of two or more types.

Among alicyclic group-containing (meth)acrylates, isobornyl (meth)acrylate is preferable, and among heterocyclic group-containing (meth)acrylates, tetrahydrofurfuryl (meth)acrylate is preferable.

The content of component (a2) in the composition for forming a buffer layer is preferably 10 to 80 parts by mass, more preferably 20 to 70 parts by mass, based on the total amount (100 parts by mass) of the composition for forming a buffer layer.

(Polymerizable compound (a3) having a functional group)

Component (a3) is a polymerizable compound containing functional groups such as hydroxyl group, epoxy group, amide group, and amino group, and is further preferably a compound having at least one (meth)acryloyl group, more preferably 1 It is a compound with two (meth)acryloyl groups.

Component (a3) has good compatibility with component (a1), making it easy to adjust the viscosity of the composition for forming a buffer layer to an appropriate range. Additionally, even if the buffer layer is relatively thin, the buffering performance becomes good.

Examples of the component (a3) include hydroxyl group-containing (meth)acrylate, epoxy group-containing compound, amide group-containing compound, and amino group-containing (meth)acrylate.

Examples of hydroxyl-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxy. Butyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenylhydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl acrylate Rates, etc. can be mentioned.

Examples of epoxy group-containing compounds include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether. Among these, glycidyl (meth)acrylate Epoxy group-containing (meth)acrylates such as methylglycidyl (meth)acrylate and methylglycidyl (meth)acrylate are preferred.

Examples of amide group-containing compounds include (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, and N-methylol. Propane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, etc. can be mentioned.

Examples of the amino group-containing (meth)acrylate include primary amino group-containing (meth)acrylate, secondary amino group-containing (meth)acrylate, and tertiary amino group-containing (meth)acrylate. .

Among these, hydroxyl-containing (meth)acrylates are preferable, and hydroxyl-containing (meth)acrylates having an aromatic ring, such as phenylhydroxypropyl (meth)acrylate, are more preferable.

In addition, component (a3) may be used individually or in combination of two or more types.

The content of component (a3) in the composition for forming a buffer layer is preferably 5 to 40 parts by mass, more preferably, with respect to the total amount (100 parts by mass) of the composition for forming a buffer layer, in order to improve the film forming property of the composition for forming a buffer layer. It is preferably 7 to 35 parts by mass, more preferably 10 to 30 parts by mass.

In addition, the content ratio [(a2)/(a3)] of component (a2) and component (a3) in the composition for forming a buffer layer is preferably 0.5 to 3.0, more preferably 1.0 to 3.0, and still more preferably 1.3. ~3.0, particularly preferably 1.5-2.8.

(Multifunctional polymerizable compound (a4))

A polyfunctional polymerizable compound refers to a compound having two or more photopolymerizable unsaturated groups. The photopolymerizable unsaturated group is a functional group containing a carbon-carbon double bond, and examples include (meth)acryloyl group, vinyl group, allyl group, and vinylbenzyl group. Two or more types of photopolymerizable unsaturated groups may be combined. When the photopolymerizable unsaturated group in the polyfunctional polymerizable compound reacts with the (meth)acryloyl group in component (a1), or the photopolymerizable unsaturated group in component (a4) reacts with each other, a three-dimensional network structure (cross-linked structure) is formed. do. When a multifunctional polymerizable compound is used, the crosslinked structure formed by energy ray irradiation is likely to increase compared to the case where a compound containing only one photopolymerizable unsaturated group is used.

In addition, there is an overlap between the definition of component (a4) and the definitions of component (a2) and component (a3) described above, but the overlapping portion is included in component (a4). For example, compounds having an alicyclic or heterocyclic group having 6 to 20 ring atoms and two or more (meth)acryloyl groups are included in the definitions of both component (a4) and component (a2). , in the present invention, the compound is included in component (a4). In addition, compounds containing functional groups such as hydroxyl groups, epoxy groups, amide groups, and amino groups, and having two or more (meth)acryloyl groups are included in the definitions of both component (a4) and component (a3), but are not included in the present invention. The above compound is assumed to be included in component (a4).

From the above viewpoint, the number of photopolymerizable unsaturated groups (number of functional groups) in the polyfunctional polymerizable compound is preferably 2 to 10, and more preferably 3 to 6.

Moreover, the weight average molecular weight of component (a4) is preferably 30 to 40,000, more preferably 100 to 10,000, and still more preferably 200 to 1,000.

Specific components (a4) include, for example, diethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate ) Acrylate, divinylbenzene, vinyl (meth)acrylate, divinyl adipic acid, N,N'-methylenebis(meth)acrylamide, etc.

In addition, component (a4) may be used individually or in combination of two or more types.

Among these, dipentaerythritol hexa(meth)acrylate is preferable.

The content of component (a4) in the composition for forming a buffer layer is preferably 2 to 40 parts by mass, more preferably 3 to 20 parts by mass, even more preferably, based on the total amount (100 parts by mass) of the composition for forming a buffer layer. It is 5 to 15 parts by mass.

(Polymerizable compounds (a5) other than components (a1) to (a4))

The composition for forming a buffer layer may contain other polymerizable compounds (a5) other than the above components (a1) to (a4), as long as the effect of the present invention is not impaired.

Examples of component (a5) include alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms; Vinyl compounds such as styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, and N-vinylcaprolactam; and the like. In addition, component (a5) may be used individually or in combination of two or more types.

The content of component (a5) in the composition for forming a buffer layer is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, even more preferably, based on the total amount (100 parts by mass) of the composition for forming a buffer layer. 0 to 5 parts by mass, particularly preferably 0 to 2 parts by mass.

(Light polymerization initiator)

The composition for forming a buffer layer preferably further contains a photopolymerization initiator from the viewpoint of shortening the polymerization time by light irradiation and reducing the amount of light irradiation when forming the buffer layer.

Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. , more specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoinmethyl ether, benzoinethyl ether. , benzoin isopropyl ether, benzylphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphos Pin oxide, etc. can be mentioned.

These photopolymerization initiators can be used individually or in combination of two or more types.

The content of the photopolymerization initiator in the composition for forming a buffer layer is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and still more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of the total amount of the energy ray polymerizable compound. It is the mass part.

(Other additives)

The composition for forming a buffer layer may contain other additives as long as they do not impair the effects of the present invention. Other additives include, for example, antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, etc. When blending these additives, the content of each additive in the composition for forming a buffer layer is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the total amount of the energy ray polymerizable compound. .

(resin component)

The composition for forming a buffer layer may contain a resin component within a range that does not impair the effect of the present invention. Examples of the resin component include polyene-thiol-based resins, polyolefin-based resins such as polybutene, polybutadiene, and polymethylpentene, and thermoplastic resins such as styrene-based copolymers.

The content of these resin components in the composition for forming a buffer layer is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, and still more preferably 0, based on the total amount (100 parts by mass) of the composition for forming a buffer layer. to 5 parts by mass, particularly preferably 0 to 2 parts by mass.

A buffer layer formed from a composition for forming a buffer layer containing an energy ray polymerizable compound is obtained by polymerizing and curing a composition for forming a buffer layer having the above composition by irradiation with energy rays. That is, the buffer layer is a cured product of the composition for forming a buffer layer.

Therefore, the buffer layer contains polymerized units derived from component (a1). In addition, the buffer layer preferably contains polymerized units derived from component (a2) and/or polymerized units derived from component (a3). Additionally, it may contain polymerized units derived from component (a4) and/or polymerized units derived from component (a5). The content ratio of each polymer unit in the buffer layer usually matches the ratio (input ratio) of each component constituting the composition for forming the buffer layer. For example, when the content of component (a1) in the composition for forming a buffer layer is 10 to 70 parts by mass based on the total amount (100 parts by mass) of the composition for forming a buffer layer, the buffer layer contains 10 to 10 polymerized units derived from component (a1). Contains 70 parts by mass. Additionally, when the content of component (a2) in the composition for forming a buffer layer is 10 to 80 parts by mass based on the total amount (100 parts by mass) of the composition for forming a buffer layer, the buffer layer contains 10 to 80 parts by mass of polymerized units derived from component (a2). Contains wealth. The same applies to components (a3) to (a5).

<Layer containing polyolefin resin film>

The buffer layer may be formed of a layer containing a polyolefin resin film.

When the buffer layer is a layer containing a polyolefin resin film, the stress relaxation property may be lower than when the buffer layer is a layer formed from a composition for forming a buffer layer containing an energy ray polymerizable compound. In this case, there is a risk that bending may occur in the adhesive tape having a buffer layer formed of a layer containing a polyolefin resin film on one side of the base material. The buffer layer formed by the layer containing the polyolefin resin film may be provided on at least one side of the substrate. However, from the viewpoint of preventing this problem, the buffer layer formed by the layer containing the polyolefin resin film should be provided on both sides of the substrate. desirable.

The polyolefin resin is not particularly limited and includes, for example, very low density polyethylene (VLDPE, density: 880 kg/m3 or more and less than 910 kg/m3), low density polyethylene (LDPE, density: 910 kg/m3 or more and less than 930 kg/m3). , medium-density polyethylene (MDPE, density: 930 kg/m3 or more but less than 942 kg/m3), high-density polyethylene (HDPE, density: 942 kg/m3 or more), polyethylene resin, polypropylene resin, polyethylene-polypropylene copolymer, Olefin elastomer (TPO), cycloolefin resin, ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl acetate-maleic anhydride copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer , ethylene-(meth)acrylic acid ester-maleic anhydride copolymer, etc.

These polyolefin resins can be used individually or in combination of two or more types.

Among the polyolefin resins, polyethylene resin is preferable and low-density polyethylene is more preferable from the viewpoint of obtaining a buffer layer with specific physical properties.

The above-described buffer layer may contain additives such as plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, and catalysts, as long as they do not impair the effect of the present invention. In addition, the above-mentioned buffer layer may be transparent or opaque, and may be colored or vapor-deposited as desired.

○ Release sheet

A release sheet may be affixed to the surface of the adhesive tape. Specifically, the release sheet is affixed to the surface of the adhesive layer of the adhesive tape. The release sheet is attached to the surface of the adhesive layer to protect the adhesive layer during transportation and storage. The release sheet is attached to the adhesive tape so as to be peelable, and is peeled and removed from the adhesive tape before the adhesive tape is used (that is, before the wafer is attached).

As the release sheet, a release sheet on which at least one side has been subjected to a release treatment is used, and specific examples thereof include those in which a release agent is applied onto the surface of the base material for the release sheet.

As the base material for the release sheet, a resin film is preferable, and examples of the resin constituting the resin film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin, and polypropylene. Polyolefin resins, such as resin and polyethylene resin, are mentioned. Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.

The thickness of the release sheet is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 150 μm.

○ Manufacturing method of adhesive tape

There is no particular limitation as to the manufacturing method of the adhesive tape of this invention, and it can be manufactured by a well-known method.

For example, the method for producing an adhesive tape having a base material, an adhesive layer provided on one side of the base material, and a buffer layer provided on the other side of the base material is as follows.

When the buffer layer is formed of a composition for forming a buffer layer containing an energy-ray polymerizable compound, the buffer layer and the base material prepared by coating and curing the composition for forming a buffer layer on a release sheet are bonded, and the release sheet is removed, thereby separating the buffer layer and the base material. A laminate is obtained. Additionally, when the buffer layer is a layer containing a polyolefin resin film, a laminate of the buffer layer and the base material is obtained by bonding the buffer layer and the base material.

Then, the adhesive layer provided on the release sheet is bonded to the base material side of the laminate, and an adhesive tape in which the release sheet is attached to the surface of the adhesive layer can be manufactured. The release sheet affixed to the surface of the adhesive layer may be appropriately peeled and removed before use of the adhesive tape.

As a method of forming the adhesive layer on the release sheet, the adhesive layer can be formed by directly applying an adhesive (adhesive composition) on the release sheet using a known application method and heating and drying the coating film.

Additionally, an adhesive layer may be formed by directly applying an adhesive (adhesive composition) to one side of the substrate. Examples of the adhesive application method include the spray coating method, bar coating method, knife coating method, roll coating method, blade coating method, die coating method, and gravure coating method, which are indicated as the manufacturing method of the buffer layer.

As a method of forming a buffer layer on a release sheet, a buffer layer can be formed by directly applying a composition for forming a buffer layer on a release sheet using a known application method to form a coating film, and then irradiating the coating film with energy rays. there is. Alternatively, the buffer layer may be formed by directly applying the composition for forming a buffer layer to one side of the substrate and drying it by heating or by irradiating the coating film with energy rays.

Examples of the application method of the composition for forming a buffer layer include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating. Additionally, in order to improve applicability, an organic solvent may be mixed with the composition for forming a buffer layer, and the composition may be applied in the form of a solution onto a release sheet.

When the composition for forming a buffer layer contains an energy ray-polymerizable compound, it is preferable to form a buffer layer by curing the coating film of the composition for forming a buffer layer by irradiating energy rays. Curing of the buffer layer may be performed in a single curing treatment or may be performed in multiple sessions. For example, the coating film on the release sheet may be completely cured to form a buffer layer and then bonded to the substrate, or the coating film may not be completely cured to form a buffer layer forming film in a semi-cured state, and the buffer layer forming film bonded to the substrate. It may be irradiated with energy rays again to completely harden to form a buffer layer. As the energy ray irradiated in the above curing treatment, ultraviolet rays are preferable. In addition, when curing, the coating film of the composition for forming a buffer layer may be exposed, but it is preferable to cure the coating film by irradiating energy rays in a state where the coating film is covered with a release sheet or a base material and the coating film is not exposed.

When the buffer layer is a layer containing a polyolefin resin film, the buffer layer and the base material may be bonded together by extrusion laminate. Specifically, the polyolefin resin constituting the buffer layer is melted and kneaded using a T-die film forming machine or the like, and the molten polyolefin resin is extruded and laminated on one side of the substrate while moving the substrate at a constant speed. Additionally, the buffer layer may be laminated directly on the substrate by heat sealing or the like. Additionally, they may be laminated through an easily adhesive layer by a method such as a dry lamination method.

In addition, a method of manufacturing an adhesive tape with a buffer layer provided on both sides of a base material includes, for example, obtaining a laminate in which the buffer layer, the base material, and the buffer layer are laminated in this order by the method described above, and then applying an adhesive to one side of the buffer layer. Just form a layer.

○ Manufacturing method of semiconductor device

The adhesive tape according to the present invention is preferably affixed to the surface of a semiconductor wafer and used when grinding the back side of the wafer. More preferably, the adhesive tape according to the present invention is preferably used in DBG where backside grinding of the wafer and separation of the wafer are performed simultaneously. Particularly preferably, the adhesive tape according to the present invention is preferably used in LDBG, where a group of chips with a small kerf width is obtained when the semiconductor wafer is separated into pieces. In addition, “chip group” refers to a plurality of semiconductor chips aligned in a wafer shape and held on the adhesive tape according to the present invention.

As a non-limiting example of the use of the adhesive tape, the manufacturing method of the semiconductor device will be described in more detail below.

The manufacturing method of a semiconductor device specifically includes at least the following steps 1 to 4.

Step 1: A process of attaching the above-mentioned adhesive tape to the surface of a semiconductor wafer and cutting the adhesive tape along the outer periphery of the semiconductor wafer.

Process 2: A process of forming a groove from the surface side of the semiconductor wafer, or forming a modified area inside the semiconductor wafer from the front or back side of the semiconductor wafer.

Step 3: A process in which an adhesive tape is attached to the surface and the semiconductor wafer on which the groove or modified area is formed is ground from the back side and divided into a plurality of chips using the groove or modified area as a starting point.

Process 4: Process of peeling the adhesive tape from the individual semiconductor wafers (i.e., multiple semiconductor chips)

Hereinafter, each step of the semiconductor device manufacturing method will be described in detail.

(Process 1)

In step 1, the adhesive tape of the present invention is affixed to the surface of a semiconductor wafer through an adhesive layer and cut along the outer periphery of the semiconductor wafer. The adhesive tape is attached so as to cover the semiconductor wafer and the outer table extending around the semiconductor wafer. Then, the adhesive tape is cut with a cutter or the like along the outer periphery of the semiconductor wafer. The cutting speed is usually 10 to 300 mm/s. The temperature of the cutter blade during cutting may be room temperature, or the cutter blade may be heated to cut.

This step may be performed before Step 2, which will be described later, or may be performed after Step 2. For example, when forming a modified region on a semiconductor wafer, it is preferable to perform step 1 before step 2. On the other hand, when forming grooves on the surface of the semiconductor wafer by dicing or the like, Process 1 is performed after Process 2. That is, the adhesive tape is attached in this process 1 to the surface of the wafer having the groove formed in process 2, which will be described later.

The semiconductor wafer used in this manufacturing method may be a silicon wafer, or may be a wafer made of gallium arsenide, silicon carbide, lithium tantalum, lithium niobate, gallium nitride, or indium phosphide, or a glass wafer. The thickness of the semiconductor wafer before grinding is not particularly limited, but is usually about 500 to 1000 μm. Additionally, a semiconductor wafer usually has a circuit formed on its surface. Circuit formation on the wafer surface can be performed by various methods, including conventionally used methods such as etching and lift-off methods.

(Process 2)

In step 2, a groove is formed from the front side of the semiconductor wafer, or a modified region is formed inside the semiconductor wafer from the front or back side of the semiconductor wafer.

The groove formed in this process is a groove whose depth is shallower than the thickness of the semiconductor wafer. The grooves can be formed by dicing using a conventionally known wafer dicing device or the like. Additionally, the semiconductor wafer is divided into a plurality of semiconductor chips along the groove in step 3 described later.

In addition, the modified area is a nitrided portion of the semiconductor wafer, and the semiconductor wafer becomes thinner due to grinding in the grinding process, or the semiconductor wafer is destroyed by applying force due to grinding, causing the semiconductor wafer to be damaged. This is the starting point for reorganization into chips. That is, in step 2, the grooves and modified regions are formed to follow the dividing line when the semiconductor wafer is divided into semiconductor chips in step 3, which will be described later.

The formation of the modified region is performed by irradiation of a laser focused on the inside of the semiconductor wafer, and the modified region is formed inside the semiconductor wafer. Laser irradiation may be performed from the front side or the back side of the semiconductor wafer. In addition, in the aspect of forming a modified region, when step 2 is performed after step 1 and laser irradiation is performed from the wafer surface, the laser is irradiated to the semiconductor wafer through the adhesive tape.

A semiconductor wafer to which an adhesive tape is attached and a groove or modified area is formed is placed on a chuck table and held by being attracted to the chuck table. At this time, the semiconductor wafer is adsorbed with its surface side placed on the table side.

(Process 3)

After Process 1 and Process 2, the back side of the semiconductor wafer on the chuck table is ground, and the semiconductor wafer is divided into a plurality of semiconductor chips.

Here, when a groove is formed in the semiconductor wafer, back side grinding is performed to thin the semiconductor wafer at least to a position reaching the bottom of the groove. By this back-side grinding, the groove becomes a notch penetrating the wafer, and the semiconductor wafer is divided by the notch and divided into individual semiconductor chips.

On the other hand, when a modified region is formed, the ground surface (back surface of the wafer) may reach the modified region by grinding, but it does not have to strictly reach the modified region. In other words, starting from the modified area, the semiconductor wafer is broken and broken into semiconductor chips by grinding to a position close to the modified area. For example, the actual separation of the semiconductor chip may be performed by attaching a pickup tape, which will be described later, and then stretching the pickup tape.

Additionally, dry polishing may be performed after completion of back grinding and prior to picking up chips.

The shape of the individualized semiconductor chip may be rectangular or may be an elongated shape such as a rectangle. Additionally, the thickness of the divided semiconductor chip is not particularly limited, but is preferably about 5 to 100 μm, and more preferably 10 to 45 μm. According to LDBG, which creates a modified area inside the wafer with a laser and separates the wafer into pieces due to stress during grinding of the back side of the wafer, the thickness of the divided semiconductor chips is 50 ㎛ or less, more preferably 10 to 45 ㎛. It becomes easier to do so. Additionally, the size of the separated semiconductor chip is not particularly limited, but the chip size is preferably less than 600 mm2, more preferably less than 400 mm2, and even more preferably less than 300 mm2.

By using the adhesive tape of the present invention, even if the semiconductor chip is thin and/or small, cracks are prevented from occurring in the semiconductor chip during peeling of the adhesive tape below (step 4).

(Process 4)

The adhesive tape is peeled from the separated semiconductor wafer (i.e., a plurality of semiconductor chips aligned in a wafer shape). This process is performed, for example, by the following method.

First, when the adhesive layer of the adhesive tape is formed of an energy ray-curable adhesive, the adhesive layer is cured by irradiating an energy ray. Next, a pickup tape is attached to the back side of the separated semiconductor wafer, and the position and orientation are adjusted to enable pickup. At this time, the ring frame placed on the outer peripheral side of the wafer is also bonded to the pickup tape, and the outer peripheral edge of the pickup tape is fixed to the ring frame. The wafer and ring frame may be bonded to the pickup tape at the same time or may be bonded at different timings. Next, the adhesive tape is peeled from the plurality of semiconductor chips held on the pickup tape.

Thereafter, a plurality of semiconductor chips on the pickup tape are picked up and fixed on a substrate or the like to manufacture a semiconductor device.

In addition, the pickup tape is not particularly limited, but is comprised, for example, of an adhesive tape including a base material and an adhesive layer provided on at least one side of the base material.

Also, instead of pickup tape, adhesive tape can be used. An adhesive tape is a laminate of a film-like adhesive and a release sheet, a laminate of a dicing tape and a film-like adhesive, or a dicing tape consisting of an adhesive layer and a release sheet that have the functions of both a dicing tape and a die-bonding tape. Die bonding tape, etc. can be mentioned. That is, in this embodiment, the step of attaching the dicing/die bonding tape to the back side of the semiconductor wafer may be included. Additionally, before attaching the pickup tape, a film-like adhesive may be attached to the back side of the separated semiconductor wafer. When using a film adhesive, the film adhesive may be of the same shape as the wafer.

Here, when the adhesive layer of the adhesive tape is formed of an energy ray-curable adhesive, when irradiated with an energy ray, the portion of the adhesive layer in close contact with the wafer is cured, and the adhesive strength of that portion is sufficiently reduced. However, in parts of the adhesive layer that are not in close contact with the wafer and are exposed to the air, curing of the adhesive is usually inhibited by oxygen in the air, and is not cured even by irradiation of energy rays such as ultraviolet rays, so the adhesive strength is not sufficiently reduced. . Therefore, as shown in FIG. 3, when the thickness of the semiconductor wafer is made extremely thin to about 30 ㎛ by back side grinding, dicing, die bonding tape, etc. are attached to the back side of the semiconductor wafer, and The uncured portion of the adhesive layer of the affixed adhesive tape is affixed in contact with the adhesive layer of the dicing or die-bonding tape. Then, when the adhesive tape attached to the dicing/die-bonding tape, etc. is to be peeled off, the adhesive tape and the dicing/die-bonding tape are integrated, and the dicing/die-bonding tape also curves along with the curvature of the adhesive tape. And, the wafer or chip sandwiched between the adhesive tape and the dicing/die bonding tape is also curved at the same time. As a result, it becomes easy for cracks to occur in the chip. Additionally, adhesive layers such as dicing and die-bonding tapes may be damaged due to curvature and their fragments may fall off.

On the other hand, according to the adhesive tape according to this embodiment, it is possible to prevent cracks from occurring in the semiconductor chip when peeling the adhesive tape. FIG. 5 is a schematic diagram of a laminate in which a dicing/die-bonding tape 30 is further attached to a back-ground ground semiconductor wafer 20 on which the adhesive tape according to the present embodiment is attached. FIG. 5 shows a case where the dicing/die bonding tape 30 is attached to a semiconductor wafer 20 that has been back ground to a very thin thickness of about 30 μm. In the adhesive tape according to this embodiment, the adhesive strength of the adhesive layer can be sufficiently reduced by irradiation of energy rays even when exposed to the atmospheric atmosphere. Therefore, as shown in Figure 5, when the thickness of the semiconductor wafer is very thin to about 30 μm by back side grinding, a part of the adhesive layer of the adhesive tape attached to the surface of the semiconductor wafer and the dicing/die bonding tape Even if the adhesive layers of the back come into contact, there is no case where both parties stick together. Therefore, the adhesive tape can be peeled off without being integrated with the dicing/die-bonding tape. As a result, chip cracking can be suppressed.

When using an adhesive tape or attaching a film adhesive to the back side of a separated semiconductor wafer before attaching a pickup tape, a plurality of semiconductor chips on the adhesive tape or pickup tape are of the same shape as the semiconductor chip. It is picked up together with the divided adhesive layer. Then, the semiconductor chip is fixed on a substrate, etc. through an adhesive layer, and a semiconductor device is manufactured. Division of the adhesive layer is performed using a laser or expander.

Above, an example of using the adhesive tape according to the present invention in a method of dividing a semiconductor wafer into pieces using DBG or LDBG has been described. However, the adhesive tape according to the present invention has a kerf width when dividing a semiconductor wafer into pieces. This can be suitably used in an LDBG in which a smaller and thinner chip group is obtained. In addition, the adhesive tape according to the present invention can be used for normal back surface grinding, and can also be used to temporarily hold a workpiece during processing of glass, ceramics, etc. Additionally, it can be used as various re-release adhesive tapes.

Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

The measurement and evaluation methods are as follows. The results are shown in Table 1.

[Surface modulus]

For adhesive tapes for semiconductor processing, one side of the adhesive layer is exposed to the atmosphere, using an ultraviolet irradiation device (manufactured by LINTEC Corporation, device name “RAD 2000”) under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2. The adhesive tape was irradiated with ultraviolet rays from the substrate side. A cantilever made of silicon nitride (“SCANASYST-AIR”, manufactured by Bruker Corporation) installed on an atomic force microscope (manufactured by Bruker Corporation, device name “Dimension Icon”), nominal tip radius: 2 nm, resonance frequency: 70 kHz, spring constant: 0.4. N/m), the surface of the adhesive layer was press-fitted at room temperature at a press-in amount of 5 nm and a scan speed of 5 Hz, and peeling was performed. The obtained force curve (the horizontal axis is the sample deformation amount and the vertical axis is the measured load) was fitted with the JKR theoretical equation to calculate the surface elastic modulus. The average value of the values obtained by measuring 4096 points on the surface of the adhesive layer (5 μm x 5 μm) was taken as the surface elastic modulus (MPa).

[Peeling evaluation]

The adhesive tape was affixed to a silicon wafer with a diameter of 12 inches and a thickness of 775 μm using a tape laminator for backgrinding (manufactured by LINTEC Corporation, device name “RAD-3510F/12”), and cut along the outer periphery of the silicon wafer. For the silicon wafer, using a laser saw (manufactured by DISCO CORPORATION, device name “DFL7361”), laser light with a wavelength of 1342 nm is irradiated from the surface of the silicon wafer so that the chip size inside the silicon wafer is 5 mm × 5 mm. A reformed zone was formed. Next, using a grinder (manufactured by DISCO CORPORATION, device name “DGP8760”), the back side of the silicon wafer was ground so that the thickness after grinding was 30 μm. At this time, the adhesive tape was sized to cover the outer periphery of the silicon wafer after grinding and was 1.0 mm larger than the outer periphery of the silicon wafer. Using an ultraviolet irradiation device (manufactured by LINTEC Corporation, device name "RAD 2000"), ultraviolet rays were irradiated to the adhesive tape from the substrate side, that is, the surface side of the silicon wafer, under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2. The adhesive layer side of a dicing die bonding tape (manufactured by LINTEC Corporation, LD01D-07) was attached to the back side of a silicon wafer while heating to 60°C using a tape mounter (manufactured by LINTEC Corporation, device name “ADWILL RAD-2700”). . The adhesive tape was peeled off. At this time, the degree of peeling of the adhesive layer of the dicing/die-bonding tape was observed and evaluated based on the following standards.

A: The peeled area is less than 70%.

B: The peeled area is 70% or more and less than 97%.

C: The peeled area is 97% or more.

[Surface free energy]

For adhesive tapes for semiconductor processing, one side of the adhesive layer is exposed to the atmosphere, using an ultraviolet irradiation device (manufactured by LINTEC Corporation, device name “RAD 2000”) under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2. The adhesive tape was irradiated with ultraviolet rays from the substrate side. Using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., device name “DM-70”), diiodomethane, 1-bromonaphthalene, and distilled water were used as droplets, and a static method was performed according to JIS R 3257. : The contact angle (measurement temperature: 25°C) was measured based on 1999, and the surface free energy (mJ/m2) was calculated by the Kitazaki and Hata method based on the contact angle value.

[Peel strength]

For an adhesive tape for semiconductor processing (width 25 mm) consisting of a base material and an adhesive layer, the illuminance was measured using an ultraviolet irradiation device (manufactured by LINTEC Corporation, device name “RAD 2000”) with one side of the adhesive layer exposed to the atmospheric atmosphere. Ultraviolet rays were irradiated from the substrate side to the adhesive tape under the conditions of 220 mW/cm2 and light quantity of 500 mJ/cm2. On the exposed side of the adhesive layer, a PMMA plate (thickness 2 mm, width 70 mm, length 150 mm, “ACRYLITE L001” manufactured by Mitsubishi Chemical Corporation) was placed on the exposed side at 23°C and 50%RH under the conditions of one round trip with a 2 kg roll. After sticking and leaving for 30 minutes, the peeling strength when peeling the adhesive tape at 180° was measured under the conditions of a measurement temperature of 25°C and a peeling speed of 300 mm/min. Measurements were made twice under the same conditions, and the average values are shown in Table 1.

[Adhesion energy]

For adhesive tapes for semiconductor processing, one side of the adhesive layer is exposed to the atmosphere, using an ultraviolet irradiation device (manufactured by LINTEC Corporation, device name “RAD 2000”) under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2. The adhesive tape was irradiated with ultraviolet rays from the substrate side. A cantilever made of silicon nitride (“SCANASYST-AIR”, manufactured by Bruker Corporation) installed on an atomic force microscope (manufactured by Bruker Corporation, device name “Dimension Icon”), nominal tip radius: 2 nm, resonance frequency: 70 kHz, spring constant: 0.4. N/m), the surface of the adhesive layer was press-fitted at room temperature at a press-in amount of 5 nm and a scan speed of 5 Hz, and peeling was performed. The obtained force curve (the horizontal axis is the sample deformation amount and the vertical axis is the measured load) was fitted with the JKR theoretical equation to calculate the surface elastic modulus. The average value of the values obtained by measuring 4096 points on the surface of the adhesive layer 5 μm × 5 μm was taken as adhesion energy (J/m 2 ).

The mass parts of the following examples and comparative examples are all converted to solid content.

<Example 1>

(1) Description

As a base material, a PET film with a double-sided easily adhesive layer (Cosmoshine A4300 manufactured by TOYOBO CO., LTD., thickness: 50 μm, Young's modulus at 23°C: 2550 MPa) was prepared.

(2) Adhesive layer

(Preparation of adhesive composition)

An acrylic polymer obtained by copolymerizing 50 parts by mass of n-butylacrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA), and the entire acrylic polymer. 2-methacryloyloxyethyl isocyanate (MOI) was reacted to add 90 mol% of hydroxyl groups to obtain an energy ray-curable acrylic resin.

For the total amount of 100 parts by mass of this energy ray curable acrylic resin, 12 parts by mass of polyfunctional urethane acrylate, which is an energy ray curable compound, 1.1 parts by mass of isocyanate crosslinking agent (manufactured by TOSOH CORPORATION, product name "Colonate L"), photopolymerized As an initiator, 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins B.V., product name "OMNIRAD TPO") was mixed and diluted with methyl ethyl ketone to obtain a solid content concentration of 32% by mass. A coating liquid for the adhesive composition was prepared.

(3) Production of adhesive tape

The coating liquid of the adhesive composition obtained above was applied to the peeled surface of a release sheet (manufactured by LINTEC Corporation, brand name "SP-PET381031"), heated and dried, and an adhesive layer with a thickness of 30 μm was formed on the release sheet. . The surface of the formed adhesive layer and the base material were bonded together to produce an adhesive tape for semiconductor processing.

<Example 2>

In the preparation of the adhesive composition, 50 parts by mass of n-butylacrylate (BA), 20 parts by mass of methyl methacrylate (MMA), 15 parts by mass of 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that 15 parts by mass of methacrylate (HEMA) was copolymerized to obtain an acrylic polymer.

<Example 3>

In preparing the adhesive composition, 60 parts by mass of ethyl acrylate (EA), 10 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) are copolymerized to obtain an acrylic polymer, As a photopolymerization initiator, instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2.4 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins B.V., product name “OMNIRAD 651”) was used. An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that the adhesive was used.

<Example 4>

In preparing the adhesive composition, 60 parts by mass of n-butylacrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) are copolymerized to form an acrylic polymer. 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins B.V., product name “OMNIRAD 651”) was obtained instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator. An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that 2.4 parts by mass was used.

<Example 5>

In preparing the adhesive composition, 65 parts by mass of n-butylacrylate (BA), 5 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) are copolymerized to form an acrylic polymer. 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins B.V., product name “OMNIRAD 651”) was obtained instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator. An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that 2.4 parts by mass was used.

<Example 6>

In preparing the adhesive composition, 60 parts by mass of 2-ethylhexyl acrylate (2EHA), 10 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) are copolymerized to form an acrylic polymer. was obtained, and instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator, 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins B.V., product name "OMNIRAD 651") ) An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that 2.4 parts by mass was used.

<Example 7>

In the preparation of the adhesive composition, 40 parts by mass of 2-ethylhexyl acrylate (2EHA), 20 parts by mass of ethyl acrylate (EA), 10 parts by mass of methyl methacrylate (MMA), and 2-hydroxyethyl methacrylate (HEMA) 30 parts by mass was copolymerized to obtain an acrylic polymer, and instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator, 2,2-dimethoxy-2-phenylacetophenone (IGM) was used. An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that 2.4 parts by mass (product name "OMNIRAD 651", manufactured by Resins B.V.) was used.

<Example 8>

In the preparation of the adhesive composition, 60 parts by mass of ethyl acrylate (EA), 10 parts by mass of methyl methacrylate (MMA), 15 parts by mass of 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl methacryl. 15 parts by mass of HEMA were copolymerized to obtain an acrylic polymer, and instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator, 2,2-dimethoxy-2-phenylacetophenone ( An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that 2.4 parts by mass (product name "OMNIRAD 651", manufactured by IGM Resins B.V.) was used.

<Example 9>

In the preparation of the adhesive composition, 60 parts by mass of n-butylacrylate (BA), 10 parts by mass of methyl methacrylate (MMA), 15 parts by mass of 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl An acrylic polymer was obtained by copolymerizing 15 parts by mass of methacrylate (HEMA), and 2,2-dimethoxy-2-phenylaceto was used instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator. An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that 2.4 parts by mass of phenone (manufactured by IGM Resins B.V., product name "OMNIRAD 651") was used.

<Example 10>

In the preparation of the adhesive composition, 52 parts by mass of n-butylacrylate (BA), 20 parts by mass of methyl methacrylate (MMA), 21 parts by mass of 2-hydroxyethyl acrylate (HEA), and 2-hydroxy An adhesive tape for semiconductor processing was produced in the same manner as in Example 1, except that 7 parts by mass of ethyl methacrylate (HEMA) was copolymerized to obtain an acrylic polymer.

<Comparative Example 1>

In preparing the adhesive composition, 52 parts by mass of n-butylacrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA) were copolymerized to obtain an acrylic polymer. Except this, an adhesive tape for semiconductor processing was produced in the same manner as in Example 1.

[Table 1]

From the above results, it can be seen that according to the adhesive tape for semiconductor processing according to the present invention, the surface elastic modulus of the adhesive layer decreases even in the air due to irradiation of energy rays such as ultraviolet rays, and the adhesive strength sufficiently decreases. Therefore, by using the adhesive tape according to the present invention, even when the thickness of the semiconductor wafer is made very thin by backside grinding, the occurrence of cracks in the semiconductor chip can be suppressed, and the productivity of the semiconductor device can be improved.

10: Adhesive tape
20: Semiconductor wafer
30: Adhesive tape (dicing/die bonding tape)
100: Adhesive tape according to this embodiment
110: Description
120: Adhesive layer

Claims (5)

An adhesive tape having a base material and an adhesive layer,
With one side of the adhesive layer exposed to the atmospheric atmosphere, the surface elastic modulus of the exposed side of the adhesive layer is 5 MPa or more after irradiating ultraviolet rays to the adhesive tape under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2, a semiconductor Adhesive tape for processing. According to paragraph 1,
The adhesive layer contains an acrylic resin,
An adhesive tape for semiconductor processing, wherein the content of polymerized units derived from HEMA is 6 parts by mass or more with respect to the total amount of the acrylic resin of 100 parts by mass. According to claim 1 or 2,
With one side of the adhesive layer exposed to the air atmosphere, the surface free energy of the exposed side of the adhesive layer after irradiating ultraviolet rays to the adhesive tape under the conditions of an illuminance of 220 mW/cm2 and a light amount of 500 mJ/cm2 is 36 mJ/㎡. Adhesive tape for semiconductor processing. A process of attaching the adhesive tape for semiconductor processing according to any one of claims 1 to 3 to the surface of a semiconductor wafer and cutting the adhesive tape along the outer periphery of the semiconductor wafer;
A process of forming a groove from the front side of the semiconductor wafer, or forming a modified region inside the semiconductor wafer from the front or back side of the semiconductor wafer;
A process of grinding a semiconductor wafer on which the adhesive tape is attached to the surface and on which the groove or the modified region is formed, from the back side, and dividing the semiconductor wafer into a plurality of chips using the groove or the modified region as a starting point;
A method of manufacturing a semiconductor device, comprising a step of peeling the adhesive tape from the plurality of chips. According to clause 4,
A method of manufacturing a semiconductor device, further comprising attaching a dicing/die bonding tape to the back side of a semiconductor wafer.